diff --git a/dot/state/block.go b/dot/state/block.go
index 3736502601..08760bb92b 100644
--- a/dot/state/block.go
+++ b/dot/state/block.go
@@ -773,10 +773,14 @@ func (bs *BlockState) IsDescendantOf(ancestor, descendant common.Hash) (bool, er
 			return false, fmt.Errorf("getting header: %w", err2)
 		}
 
-		for current := descendantHeader; descendantHeader.Number < ancestorHeader.Number; {
+		for current := descendantHeader; current.Number > ancestorHeader.Number; {
 			if current.ParentHash == ancestor {
 				return true, nil
 			}
+			current, err2 = bs.GetHeader(current.ParentHash)
+			if err2 != nil {
+				return false, fmt.Errorf("getting header: %w", err2)
+			}
 		}
 
 		return false, nil